I've just cleaned off my MAF sensor. Really simple job but I'm not sure if it's worked to full effect. There is definately a noticable difference at the lower end but there is still hesitation throughout the rev range. So guess it's down to either the throttle body, collant temp sensor or crimped hoses?! It's going to the garage on Saturday so my pocket is going to feel the wrath.

 

Got my problem sorted to an extent. Had a new MAF fitted and it has made a huge difference. Cleared down 4 fault codes in the ECU too which can't have been helping. Still not QUITE right, think she needs a tune-up.
Should be an £80 job really.

 

Thanks for the updates - just thought I'd mention this as another possibility for anybody else having this problem.

The air intake runs from the front grille to the air filter box, with the pipe consisting of two sections joined about half way along. I discovered that the rubber seal around this join was badly perished and disintegrating.

Given that the join is a very loose fit, movement during driving would mean that some air is drawn from the engine compartment (hot) and some from the front of the car (cool) in varying proportions, particularly if hard acceleration causes a greater vacuum. As far as I can tell, the MAF is very sensitive and thus this kind of erratic temperature fluctuation could cause these type of symptoms as the MAF readings vary rapidly and the fuel system tries to compensate.

Duct-taping the join so that it is once again air-tight seems to have improved things significantly, but I'll have to wait for a few days and see what happens.

 

To continue the saga...

Recently things got much worse to the point where power was reduced so much the car would barely accelerate. Taking it to the local dealer revealed that it was in fact the engine speed sensor that was faulty rather than the MAF. Replacing it has completely sorted things out.

I suppose any of the sensors (engine speed, road speed, MAF, temperature, clutch switch, etc) going wrong could cause similar problems through causing the ECU to wrongly adjust the fuel injection or ignition settings.

Hopefully all should be ok from now on...

 

hey ill having the same problem in my a3...except its when im at a standing start and then i try to accelerate..seems like something is trying to hold bakc the gears...just curious how much it cost you and could there be a simple do it yourself answer?

 

Mine was still under (second hand) warranty so the dealer I bought it from replaced the engine speed sensor for free.

However, I doubt it would have cost very much - it's just a case of unclipping/unscrewing the sensor from the transmission casing and putting a new one in, and the sensor itself can't cost a lot. It would be easy to do it yourself with a decent service manual like Haynes.

First though you have to find out which sensor (if any) is causing the problem by getting somebody to read the error codes from the ECU. Audi dealers and probably quite a few independents should have the kit to do this, or again you could do it yourself by getting hold of the right equipment. There's lots of information about this kind of thing on various Audi forums and websites.

Hope this helps.